1. Field of the Invention
The invention relates to a preparation in film form which makes biphasic release of substances contained therein to liquid surroundings possible. The invention also includes a process for the production of such preparations, and the use thereof for the release of substances, in particular of drugs, to body fluids in the human or animal body.
2. Description of the Related Art
Applications based on targeted delivery or release of active ingredients or constituents to the surrounding medium depend, in certain cases—for example on administration of medicines from depot pharmaceutical forms—on a high initial dose being released at the start, followed by a lower subsequent or maintenance dose which is, however, constant over a certain period. This is intended to have the effect of very quickly building up a high level of active ingredient in the body fluids, which can then be kept at a desired level by constant administration of the maintenance dose.
In order to achieve rapid release, a preparation or formulation for example of a drug must be designed so that it has a large surface area in relation to the volume. This means that the diffusion pathways are as short as possible, and release of the active ingredient can take place in a very short time. In addition, such a release system ought to be as compact as possible in order to ensure sufficient strength and ease of handling.
A dosage form in film form which contains active ingredients in dissolved, emulsified or suspended form makes it possible, because of the small layer thickness and the correspondingly short diffusion pathways, for release times to be extremely short and thus for delivery of initial doses to be rapid.
The release of the active ingredient can take place either by the latter diffusing out of the matrix in film form, or by the film layer being dissolved or decomposed and the active ingredient thus entering the surroundings.
Active ingredient-containing films whose matrix is based on hydrophilic polymers are already known. These dosage forms in film form may also contain other constituents or auxiliaries to adjust the physicochemical parameters of the film, and the taste or the chemical stability. Films of this type are generally produced by coating an active ingredient- and auxiliary-containing solution of a hydrophilic polymer onto an inert processing sheet. The solvent is then removed by drying, and the active ingredient-containing matrix remains behind as film.
As described, it is also possible with only single-phase dosage forms to achieve rapid release of active ingredient, although in this case delivery of the initial dose is usually followed by an unwanted rapid decline in the effect. There is moreover the risk of overdosage or—in the case of active ingredients which are characterized by an increased concentration-dependent elimination—a wasted dose scenario.